Treatment of gas distribution systems



Patented July 25, 1939 PATENT OFFICE TREATMENT OF GAS DISTRIBUTIONSYSTEMS Duncan B. Williams, Glen Ridge, N. J., assignor to The UnitedGas Improvement Company, a corporation of Pennsylvania No Drawing.Application October 4, 1937, Serial No. 167,316

6 Claims.

This application is a continuation-in-part of my copending applicationSerial Number 673,618 filed May 31, 1933, now Patent 2,094,691 issuedOctober 5, 1937, and pertains generally to the treatment of theinteriors of gas mains or other gas conduits for the purpose, amongother things, of laying dust.

Systems for the distribution of gas generally consist of conduits ormains usuallylaid underground. Until recently when welded joints havecome into more common use, these conduits were constructed of sectionsof pipe, usually of cast iron, joined by means of bell and spigot orother joints. Bell and spigot joints were in many cases packed withhemp, jute, flax or other cellulosic fiber material, and sealed withlead or cement in a well-known manner. Treatment of gas conduits havingfiber packed joints involves swelling of the fiber packing as describedand claimed in my above mentioned copending application. This inventionpertains more particularly to the treatment of gas conduits having otherthan fiber packed joints.

Manufactured gas for a long period of years has been produced for themost part locally, that is, in or near the cities to be supplied, anduntil recently no special effort has been made to recover condensiblematerials from the gas prior to its delivery to the mains.

Since the gas during its manufacture is passed through the wash box andpurifying apparatus containing large quantities of moisture, it is upondelivery to the mains more or less saturated with water and is generallyreferred to as being wet.

The lower temperatures of the mains, particularly during cool weather,causes considerable condensation of water as well as other materialsknown generally as drip oil.

Over a period of years this condensed water, together with otherconstituents of the gas, such as carbon dioxide, hydro-gen sulfide,hydrocyanic acid, naphthalene, etc., has caused extensive corrosion ofthe interior walls of the mains. The products of corrosion have built upon the walls of the mains and in many instances large quantities havebecome disconnected and have collected along the bottom.

Due to the presence of the relatively large quantities of moistureresponsible for the corrosion in the first instance, the products ofcorrosion were maintained in a wet condition and did not tend to formdust in any appreciable quantity.

Therefore, until high pressure distribution came into practice and whilethe use of natural gas, or natural gas mixtures, was less wide-spread,

very little difficulty was experienced with the formation of dust in themains from the products of corrosion. In fact, traps or drips wereinstalled at low points in the mains to catch condensed hydrocarbons,known collectively as drip oil as well as the condensed water.

However, when manufactured gas is compressed to obtain a sufficientlyhigh pressure for delivery in large quantities at distant points,considerable quantities of moisture (which term is used collectively forall condensible materials) are condensed out. When this gas isre-expanded at its destination for local distribution, its relativemoisture content is low and the gas is referred to as being dry. Thereis then no longer sufficient moisture in the gas to keep the products ofcorrosion wetted down. On the contrary, the gas is so dry that it willdraw out any remaining moisture in and on the corrosion products.

In other words, as long as the main is used for distributing ordinarymoist manufactured gas, very little trouble with dust resulting fromcorrosion is experienced. However, when the service is changed over to amanufactured gas of low moisture content, or over to natural gas whichis characterized by a very low moisture content, the moisture on and inthe corrosion products dries out, and such products become a serioussource of dust.

The presence of considerable quantities of dust in the gas flowingthrough the mains of a distribution system is very undesirable becausedust tends to clog up customers service connections, interferes with theproper operation of meters and tends to clog up burners and pilotoutlets.

Under extreme conditions corrosion may be so severe as to form a seriousobstruction in the main itself by reducing its effective cross sectionalarea, or by accumulation of dust in piles in the main.

A number of methods of correcting dust troubles have been proposed andused.

For instance, excavations have been made at suitably spaced points alongthe main, say every three hundred feet, the main severed at eachexcavation and the accumulations removed mechanically.

This has been done by dragging a ball of chain back and forth throughthe disconnected section and increasing the size of the ball as more andmore of the products of corrosion have been removed. In some instances acutter has been substituted for the ball of chain.

In another method a compressor is converted to function as a suctiondevice for sucking air Steam has been introduced into the main while inservice but this method has the disadvantage that the deposited moisturedries out as soon as a steaming is stopped. As far as I am aware, the Isame applies to the fogging of oil into the mains, since the oil whichit has been necessary to use for successful fogging has had to be solight as h to make it appreciably volatile.

Furthermore, since the corrosion products comprise not only ordinaryiron rust but also a variety of other compounds resulting from theactivity of hydrogen sulfide, hydrocyanic acid, naphthalene and othercorrosive substances, the problem of wetting down the dust, of wettingthe main Wall and of thoroughly spreading a dust laying liquid becomes amajor factor.

I have discovered that a certain class of liquids generally, and certainliquids within this class more particularly, are excellently adapted asdust laying agents for treatment of gas conduits, and that gas conduitstreated with such liquids are maintained dormant as sources of dust forvery long periods of time, if not permanently.

Broadly, a liquid to be suitable for the purposes of my invention,should have certain properties.

The liquid should be substantially non-volatile; that is, it should havea relatively high boiling point and a low vapor pressure so thatevaporation is negligible even when the main is used for conducting verydry gas.

1 The liquid should be chemically and physically inert with respect tothe gas; that is, the gas should have substantially no affinity for theliquid.

The liquid should preferably be hygroscopic so that the presence ofmoisture will assist rather than resist thorough and complete wetting ofthe main walland of the corrosion products by the liquid. In thisconnection, it is to be observed that liquids of the prior art such asdrip oil or petroleum oil are non-hygroscopic in character, and arecharacterized by being completely non-miscible with water. Since it is awell recognized fact that when a solid is contacted with two immiscibleliquids, one of the liquids Will wet'the solid to the exclusion of theother,

and since this'phenomenon has been shown to apply particularly tomineral oil and water, it will be seen that thorough and completedistribution of a mineral oil is not possible in the presence of even atrace of water. It will be recognized that the surfaces of corrosionproducts in the mains may become sufiiciently dry to cause serious dusttroubles without the entire mass losing its water content. Therefore,the importance of this property in my treating liquids cannot beoverestimated. a V

The liquid preferably has good surface wetting properties with respectto both the products of corrosion and the uncorroded metal walls of themain. This will facilitate spreading of the liquid throughout themainand the body of corrosion products even when contact with the liquidis only over a small area, say along the bottom of the main.

Amixture of various liquids may be used.

interior of the conduit may be employed.

In accordance with my invention liquids having the above-mentioneddesirable properties comprises the high boiling water miscible alcohols.

In this group I include monohydroxy, dihydroxy and polyhydroxy alcohols.5

Among the monohydroxy alcohols I prefer those containing eight or morecarbon atoms, such as octyl, lauryl, and cetyl alcohol. In this groupalso fall the alkoxy alcohols, such as the higher monoalkyl ethers ofthe glycols, the monoamyl ether of ethylene glycol being an example, andthe alkoxy alkenoxy alcohols, such as the monoalkyl ethers of thepolyglycols, examples being the monoethyl ether of diethylene glycol,the monoethyl ether of triethylene glycol, and the monobutyl ether ofdiethylene glycol.

The dihydroxy alcohols include the glycols and pclyglycols of the 1-2series, such as ethylene glycol, diethylene glycol, triethylene glycol,propylene glycol, and dipropylene glycol.

The polyhydroxy alcohols include the glycerols, polyglycerols, andglycerol alkyl ethers.

The lower monohydroxy alcohols are generally not suitable to be usedalone because they are too volatile. However, these and other volatileliquids which are good solvents are not to be excluded since they may beused as solvents for less volatile, more viscous liquids falling withinthe groups before enumerated to facilitate their application to theconduit walls and to the products of corrosion. V

The treating liquid may be applied to the interior surface of a pipesection before, during, or after its installation in the main orconduits in any desired manner, such as by spraying, brushing orotherwise.

If the main or conduit is already in service,

sections of the conduit may be blocked off by means or inflated bags orother means, and the sections then completely filled with the liquid,after which the liquid can be drawn off and reused. Also, the liquid maybe sprayed into the gas by the fogging process already mentioned so thatthe corrosion products absorb the liquid from the gas stream and theliquid is deposited from the gas stream onto the walls of the conduit.In another method of application, the liquid is introduced into the mainat high points and allowed to run by gravity to low points where theexcess can be drawn off. Another method comprises inserting a longlength of hose into the main with a spray at its end or with a pluralityof sprays or openings distributed along its length, and pumping thetreating liquidinto the hose while withdrawing the hose either continu-'ously or intermittently or otherwise, or while the hose remainsstationary.

In the last three methods of application, service on the line need notbe interrupted, and the entire deposit of corrosion products as well asthe walls of the mains become coated with the treating liquid. Thewetting qualities of the treating liquid cause it to spread and wetexposed surfaces. This wetting of finely divided materials causes themto be boundtogether in a mass which prevents them from rising in a dustregardless of the velocity of the gas travelling through the conduit.The clogging of mains, meters, regulators and appliances is thuseffectively prevented.

The presence of water does not interfere with but actually assists thespreading of the treating liquid.

Any other means for applying the liquid to the As previously stated, thepresence of Water assists the wetting and spreading of the treatingliquids. If desired, therefore, water may be employed to assist in thewetting and spreading of these liquids such as by first wetting withwater, for instance, steaming, following by application of the treatingliquid, or water may be added to the treating liquid, or otherwiseemployed in the treatment. The substantially universal and excellentwetting qualities of water are thus added to those of the treatingliquids.

By the term water miscible as used in the claims is meant miscible withwater in large quantity at ordinary temperatures.

It is to be understood that the above particular description is by Wayof illustration and that changes, omissions, additions, substitutionsand/or modifications may be made within the scope of the claims withoutdeparting from the spirit of the invention.

I claim:

1. A method for treating the interior of a gas conduit having other thanfiber packed joints to lay dust, comprising coating dust sources Withinsaid conduit with an alcohol selected from a group consisting of octylalcohol, lauryl alcohol, cetyl alcohol, monoamyl ether of ethyleneglycol, monoethyl ether of diethylene glycol, monoethyl ether oftriethylene glycol, monobutyl ether of diethylene glycol, ethyleneglycol, di-

ethylene glycol, triethylene glycol, propylene glycol, and dipropyleneglycol.

2. A method for treating a gas conduit having other than fiber packedjoints to lay dust, comprising coating dust sources within said conduitwith a liquid comprising a water miscible high boiling alcohol.

3. A method for treating a gas conduit having other than fiber packedjoints to lay dust comprising wetting down dust sources Within saidconduit with a liquid comprising ethylene glycol.

4. A method for treating a gas conduit having other than fiber packedjoints to lay dust comprising, wetting down dust sources within saidconduit with a liquid comprising diethylene glycol. 1

5. A gas conduit with other than fiber packed joints having its interiordust sources wetted down by a water miscible high boiling alcohol.

6. A gas conduit with other than fiber packed joints having its innerwalls coated with an alcohol selected from a group consisting of octyla1- cohol, lauryl alcohol, cetyl alcohol, monoamyl ether of ethyleneglycol, monoethyl ether of diethylene glycol, monoethyl ether oftriethylene glycol, monobutyl ether of diethylene glycol, ethyleneglycol, diethylene glycol, triethylene glycol, propyleiie glycol, anddipropylene glycol.

DUNCAN B. WILLIAMS.

